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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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30 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Anomalous cosmic ray interaction events for investigations in the SSC and Space Station era - 'Long lived she-devil phenomena'

Observational data on anomalous cosmic-ray interaction events are compiled, classified, and briefly characterized. The events are divided into three groups: those confirmed by later observation or experiment, those shown to be the result of observational or analytical error, and those still unexplained. Among the phenomena in the latter group are magnetic-monopole candidates, fractionally charged particles, massive stable particles, anomalons, proton-decay and neutron-oscillation candidates, muon bundles, narrow showers, anomalous photons, fanlike phenomena, quark-gluon-plasma candidates, and anomalous long-range delta rays.

Takahashi, Y.↗
NASA NTRS1986

Physics through the 1990s: Nuclear physics

The volume begins with a non-mathematical introduction to nuclear physics. A description of the major advances in the field follows, with chapters on nuclear structure and dynamics, fundamental forces in the nucleus, and nuclei under extreme conditions of temperature, density, and spin. Impacts of nuclear physics on astrophysics and the scientific and societal benefits of nuclear physics are then discussed. Another section deals with scientific frontiers, describing research into the realm of the quark-gluon plasma; the changing description of nuclear matter, specifically the use of the quark model; and the implications of the standard model and grand unified theories of elementary-particle physics; and finishes with recommendations and priorities for nuclear physics research facilities, instrumentation, accelerators, theory, education, and data bases. Appended are a list of national accelerator facilities, a list of reviewers, a bibliography, and a glossary.

Source record↗
NASA NTRS1987

Statistical analysis of secondary particle distributions in relativistic nucleus-nucleus collisions

The use is described of several statistical techniques to characterize structure in the angular distributions of secondary particles from nucleus-nucleus collisions in the energy range 24 to 61 GeV/nucleon. The objective of this work was to determine whether there are correlations between emitted particle intensity and angle that may be used to support the existence of the quark gluon plasma. The techniques include chi-square null hypothesis tests, the method of discrete Fourier transform analysis, and fluctuation analysis. We have also used the method of composite unit vectors to test for azimuthal asymmetry in a data set of 63 JACEE-3 events. Each method is presented in a manner that provides the reader with some practical detail regarding its application. Of those events with relatively high statistics, Fe approaches 0 at 55 GeV/nucleon was found to possess an azimuthal distribution with a highly non-random structure. No evidence of non-statistical fluctuations was found in the pseudo-rapidity distributions of the events studied. It is seen that the most effective application of these methods relies upon the availability of many events or single events that possess very high multiplicities.

Mcguire, Stephen C.↗
NASA NTRS1988

Fluctuation analysis of relativistic nucleus-nucleus collisions in emulsion chambers

An analytical technique was developed for identifying enhanced fluctuations in the angular distributions of secondary particles produced from relativistic nucleus-nucleus collisions. The method is applied under the assumption that the masses of the produced particles are small compared to their linear momenta. The importance of particles rests in the fact that enhanced fluctuations in the rapidity distributions is considered to be an experimental signal for the creation of the quark-gluon-plasma (QGP), a state of nuclear matter predicted from the quantum chromodynamics theory (QCD). In the approach, Monte Carlo simulations are employed that make use of a portable random member generator that allow the calculations to be performed on a desk-top computer. The method is illustrated with data taken from high altitude emulsion exposures and is immediately applicable to similar data from accelerator-based emulsion exposures.

Mcguire, Stephen C.↗
NASA NTRS1990

Electric dipole moment of the electron and of the neutron

It is shown that if Higgs-boson exchange mediates CP violation a significant electric dipole moment for the electron can result. Analogous effects can contribute to the neutron's electric dipole moment at a level competitive with Weinberg's three-gluon operator.

Barr, S. M.↗
NASA NTRS1991

Cosmic rays from primordial black holes

The quark and gluon emission from primordial black holes (PBHs) which may have formed from initial density perturbations or phase transitions in the early universe are investigated. If the PBHs formed from scale-invariant initial density perturbations in the radiation dominated era, it is found that the emission can explain or contribute significantly to the extragalactic photon and interstellar cosmic-ray electron, positron, and antiproton spectra around 0.1-1 GeV. In particular, the PBH emission strongly resembles the cosmic-ray gamma-ray spectrum between 50 and 170 MeV. The upper limits on the PBH density today from the gamma-ray, e(+), e(-), and antiproton data are comparable, provided that the PBHs cluster to the same degree as the other matter in the Galactic halo.

Macgibbon, Jane H.↗
NASA NTRS1996

Squeezed States, Uncertainty Relations and the Pauli Principle in Composite and Cosmological Models

The importance of not only uncertainty relations but also the Pauli exclusion principle is emphasized in discussing various 'squeezed states' existing in the universe. The contents of this paper include: (1) Introduction; (2) Nuclear Physics in the Quark-Shell Model; (3) Hadron Physics in the Standard Quark-Gluon Model; (4) Quark-Lepton-Gauge-Boson Physics in Composite Models; (5) Astrophysics and Space-Time Physics in Cosmological Models; and (6) Conclusion. Also, not only the possible breakdown of (or deviation from) uncertainty relations but also the superficial violation of the Pauli principle at short distances (or high energies) in composite (and string) models is discussed in some detail.

Terazawa, Hidezumi↗
NASA NTRS2003

Production of Pions in pA-collisions

Accurate knowledge of pion production cross section in PA-collisions is of interest for astrophysics, CR physics, and space radiation studies. Meanwhile, pion production in pA-reactions is often accounted for by simple scaling of that for pp-collisions, which is not enough for many real applications. We evaluate the quality of existing parameterizations using the data and simulations with the Los Alamos version of the Quark-Gluon String Model code LAQGSM and the improved Cascade-Exciton Model code CEM2k. The LAQGSM and CEM2k models have been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.

Moskalenko, I. V.↗
NASA NTRS2002

CEM2k and LAQGSM Codes as Event-Generators for Space Radiation Shield and Cosmic Rays Propagation Applications

Space radiation shield applications and studies of cosmic ray propagation in the Galaxy require reliable cross sections to calculate spectra of secondary particles and yields of the isotopes produced in nuclear reactions induced both by particles and nuclei at energies from threshold to hundreds of GeV per nucleon. Since the data often exist in a very limited energy range or sometimes not at all, the only way to obtain an estimate of the production cross sections is to use theoretical models and codes. Recently, we have developed improved versions of the Cascade-Exciton Model (CEM) of nuclear reactions: the codes CEM97 and CEM2k for description of particle-nucleus reactions at energies up to about 5 GeV. In addition, we have developed a LANL version of the Quark-Gluon String Model (LAQGSM) to describe reactions induced both by particles and nuclei at energies up to hundreds of GeVhucleon. We have tested and benchmarked the CEM and LAQGSM codes against a large variety of experimental data and have compared their results with predictions by other currently available models and codes. Our benchmarks show that CEM and LAQGSM codes have predictive powers no worse than other currently used codes and describe many reactions better than other codes; therefore both our codes can be used as reliable event-generators for space radiation shield and cosmic ray propagation applications. The CEM2k code is being incorporated into the transport code MCNPX (and several other transport codes), and we plan to incorporate LAQGSM into MCNPX in the near future. Here, we present the current status of the CEM2k and LAQGSM codes, and show results and applications to studies of cosmic ray propagation in the Galaxy.

Mashnik, S. G.↗
NASA NTRS2003

Antiproton Production by CR on Air Nuclei

Recent measurements of the cosmic ray (CR) antiproton flux have been shown to challenge existing CR propagation models. In particular, the conventional reacceleration model designed to match secondary/primary nuclei ratios produces too few antiprotons. Recently there appear some indications that the atmospheric contribution to antiproton production is considerably underestimated, which implies that antiproton CR flux might be lower. This may be the primary reason of the discrepancy discovered in CR propagation. We use the Los Alamos version of the Quark-Gluon String Model code LAQGSM together with available data on antiproton production on nuclei to analyse the accuracy of existing parameterizations of antiproton production cross section. The LAQGSM model has been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.

Maskalenko, I. V.↗
NASA NTRS2003

Evaluation of Production Cross Sections of Li, Be, B in CR

Accurate evaluation of the production cross section of light elements is important for models of cosmic ray (CR) propagation, galactic chemical evolution, and cosmological studies. However, the experimental spallation cross section data are scarce and often unavailable to CR community while semi-empirical systematics are frequently wrong by a significant factor. Running sophisticated nuclear codes is not an option of choice for everyone either. We use the Los Alamos versions of the Quark-Gluon String Model code LAQGSM and the improved Cascade-Exciton Model code CEM2k together with all available data from Los Alamos Nuclear Laboratory (LANL) nuclear database to produce evaluated production cross sections of isotopes of Li, Be, and B suitable for astrophysical applications. The LAQGSM and CEM2k models have been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.

Moskalenko, I. V.↗
NASA NTRS2003

RX J1856.5-3754: A Strange Star with Solid Quark Surface?

The featureless spectra of isolated 'neutron stars' may indicate that they are actually bare strange stars but a definitive conclusion on the nature of the compact objects cannot be reached until accurate and theoretically calculated spectra of the bare quark surface are known. However due to the complex nonlinearity of quantum chromodynamics it is almost impossible to present a definitive and accurate calculation of the density-dominated quark-gluon plasma from the first principles. Nevertheless it was suggested that cold quark matter with extremely high baryon density could be in a solid state. Within the realms of this possibility we have fitted the 500ks Chandra LETG/HRC data for the brightest isolated neutron star RX 51856.5-3754 with a phenomenological spectral model and found that electric conductivity of quark matter on the stellar surface is about 1.5 x 10(exp 16)/s.

Zhang, Xiaoling↗